In recent years, a technique has been developed to evaluate the effect and the safety in the development of new pharmaceuticals and model tests of cardiac diseases such as arrhythmia by using cardiomyocytes and cardiomyocytes sheets made according to cell culturing technique. In particular, the cardiac toxicity test for evaluating toxicity and side effects on the heart and cardiac muscles is required to be carried out for all of the drugs, and the nonclinical test method using culturing cells is expected to be used as an alternative method replacing test methods involving animal experiments.
Examples of cardiomyocytes evaluation methods include an electrode array (micro electrode arrays: MEA) method (see, for example, PTL 1) and a method using image processing technique such as a calcium imaging method (see, for example, PTL 2). The MEA method is a method of performing evaluation by making use of the fact that the contraction and relaxation motions of cardiomyocytes are controlled by inflow and outflow of Na+, Ca2+, K+ in and out of the cells, and evaluating a membrane potential change caused by this inflow and outflow of the ions. On the other hand, the calcium imaging method is a method of staining cells using pigments (calcium fluorescent indicator) emitting fluorescence by bonding with calcium ions, and observing the fluorescence using a fluorescent microscope and the like.